Finite Square-well potential

Main Question or Discussion Point

Consider a finite square-well potential well of width 2.8 multiplied by 10-15 m that contains a particle of mass 1.9 GeV/c2. How deep does this potential well need to be to contain three energy levels? (Except for the energy levels, this situation approximates a deuteron. Use the infinite square well potential result to approximate the energy levels.) I don't understand this question at all and need help.